1. Field of the Invention
The present invention relates to a resin-encapsulated semiconductor device in which heat dissipation characteristic and mounting strength to a substrate are improved, and a method of manufacturing the resin-encapsulated semiconductor device.
2. Description of the Related Art
Resin-encapsulated semiconductor devices represented by power semiconductors need to have heat dissipation characteristics, and generally have the structure in which the back surface of a die pad is exposed from an encapsulating resin in order to efficiently release, to a mounting substrate, heat generated by a semiconductor chip. For example, a resin-encapsulated semiconductor device called an HSOP is registered in the international standards (JEDEC: MS-012). In the resin-encapsulated semiconductor device of such type, heat generated by the semiconductor chip is transferred to the mounting substrate from a heat dissipation plate exposed from the encapsulating resin, thereby being emitted to the outside of the semiconductor device. This enables obtainment of intended heat dissipation characteristics. In addition, as a method of improving heat dissipation characteristics, there is proposed a technology in which a die pad and inner leads are coupled to each other such that heat is released to a mounting substrate through outer leads connected to the inner leads (for example, see Japanese Patent Application Laid-open No. Hei 11-297916).
FIG. 5A to FIG. 5C are views of a related-art resin-encapsulated semiconductor device. FIG. 5A is a front surface perspective view. FIG. 5B is a back surface perspective view. FIG. 5C is a sectional view taken along the cutting line A-A illustrated in FIG. 5B. In the resin-encapsulated semiconductor device illustrated in FIG. 5A to FIG. 5C, a semiconductor chip 7 is mounted on a die pad 1 with die attach paste 6, and heat dissipation leads 19 extended from the die pad 1 are arranged on both the sides of the die pad. Further, terminals each including an inner lead 3 and an outer lead 2 are provided at the corner portions of the die pad 1. The terminals sandwich the heat dissipation lead 19 and are electrically connected to the semiconductor chip 7 through wires 5.
The semiconductor chip 7, the inner leads 3, and the wires 5 are covered with an encapsulating resin 8, and a heat dissipation surface 10 of the die pad 1, the outer leads 2, and the heat dissipation leads 19 are exposed from the encapsulating resin 8.
In the resin-encapsulated semiconductor device disclosed in Japanese Patent Application Laid-open No. JP11-297916, the semiconductor chip 7 is mounted at the center of the die pad 1, and the heat dissipation leads 19 are arranged near the semiconductor chip 7. Thus, satisfactory heat dissipation characteristics may be obtained. However, the inner leads 3 provided at the corner portions of the semiconductor device are away from the semiconductor chip, and the wires to be used for electrical connection tend to be long. Expensive wires, e.g., gold wires, are used as the wires, which greatly contributes to a package cost. There is also a problem in that the increase in electrical resistance increases power consumption, helping heat accumulation in the package.